Distal femoral jig assembly

ABSTRACT

A cutting apparatus for resecting a distal face of a femur prior to implanting a femoral component of a total knee prosthesis, comprises an elongate rod adapted for inserting into an intramedullary canal of the femur, a distal femoral cutting block, and a distal femoral jig assembly. The jig assembly can position the distal femoral cutting block on either left leg or right leg. It includes a distal femoral jig having at least one passage for slidingly receiving the rod with a preset valgus angle and a distal end face being adapted for abutting against on the distal face of the femur of either left leg or right leg dependent on its two flip orientations.

CROSS REFERENCE TO RELATED APPLICATION

This application is a National Stage 35 U.S.C. 371 of InternationalPatent Application PCT/EP2014/057404 filed Apr. 11, 2014, claimingpriority to Chinese application 201310140826.3, filed Apr. 12, 2013.

BACKGROUND OF THE INVENTION

The invention relates to a distal femoral cutting apparatus forresecting a distal face of a femur at a preset valgus angle relative toa patient's intramedullary canal prior to implanting the femoralcomponent of a total knee prosthesis.

The invention also relates to a distal femoral jig assembly used for thementioned distal femoral cutting apparatus.

Knee joint is the biggest and most complicated joint in a human body.Total knee replacement (TKR) is adopted for severely damaged knee joint.As the knee replacement becomes the most popular surgery for severe kneeinjuries, research related to TKR are attracting more and moreattention.

TKR surgery involves implantation of articulating femoral and tibialcomponents to distal femur and proximal tibia, respectively. Since afemur projects distally in an inward manner at a valgus angle relativeto the anatomic axis of the human body and a distal face of the femurhas a fossa intercondylaris and is not a planar face, the femur must beresected to conform to the size and shape of the respective prostheticcomponent so as to properly affix to the prosthetic component. The term“valgus angle” means the angle between the axis of the main body and thechannel being considered. In the case of the femur, the valgus angle isthe angle formed between the anatomic axis of the patient and thelongitudinal axis of the femur, and in the case of the jig, the valgusangle means the angle between the axis of the jig and the passages inthe jig.

A plurality of instruments and/or jigs for resecting the distal femurhave been developed. Many of the instruments include a cutting blockthat references an intramedullary rod inserted in the intramedullarycanal of the femur. However, such instruments usually cannot provideeasily adjustable jig assembly to accommodate to different patients.Meanwhile, due to the distal femur has an asymmetrical shape, the designof the instruments for TKR surgery has to take that into considerationand thereby resulting in complicated structures.

US-A-2010/0057088 relates to a distal femoral cutting apparatus whichcan be used for resecting either the left or right femur. The apparatushas a handle 12, a sword 14, a base cartridge 26 and a face plate 28connected by mating threaded connectors so that the various parts can beinterchanged with similar parts having different physical propertiessuch as angular orientation. In other words, if the surgeon wants toadjust the valgus angle of the apparatus relative to the anatomic axisof the patient, he or she has to change the corresponding parts of theapparatus on the site. For a surgical procedure, it is rathercumbersome.

BRIEF SUMMARY OF THE INVENTION

It would be desirable to provide a distal femoral cutting apparatuswhich can be used for resecting either the left or right femur witheasily adjustable valgus angles.

The present invention also provides a distal femoral jig assembly havinga flip feature and suitable for use for the mentioned distal femoralcutting apparatus.

The present invention also provides a distal femoral cutting apparatuswhich can be used for resecting either left or right femur with a distalfemoral jig assembly having a flip feature. Such flip feature allows thedistal femoral cutting apparatus to resect one of the left and rightfemurs at the first flip orientation and to resect the other one of theleft and right femurs at a second flip orientation by a simple flippingaction.

The invention also provides a distal femoral jig assembly is used with acutting apparatus for resecting a distal face of a femur prior toimplanting a femoral component of a total knee prosthesis, the cuttingapparatus comprising a rod adapted for inserting into an intramedullarycanal of the femur, and a distal femoral cutting block configured forguiding resection of the distal face of the femur, in which the distalfemoral jig assembly is capable of positioning the distal femoralcutting block on either left leg or right leg and comprising a distalfemoral jig, the distal femoral jig comprising at least one passage forslidingly receiving the rod with a preset valgus angle and a distal endface being adapted for abutting against on the distal face of the femurof either left leg or right leg dependent on its two flip orientations:in a first flip orientation the rod can be inserted in a selected one ofthe at least one passage having the preset valgus angle for one of theleft and right legs, and in a second flip orientation after the distalfemoral jig being flipped over about 180° about a jig longitudinal axisthe rod can be inserted in a selected one of the at least one passagehaving the preset valgus angle for the other one of the left and rightlegs

The invention therefore provides cutting apparatus for resecting adistal face of a femur prior to implanting a femoral component of atotal knee prosthesis, comprising:

-   -   (a) an elongate rod adapted for inserting into an intramedullary        canal of the femur,    -   (b) a distal femoral cutting block configured for guiding        resection of the distal face of the femur,    -   (c) a distal femoral jig assembly capable of positioning the        distal femoral cutting block on either left leg or right leg and        comprising a distal femoral jig, the distal femoral jig        comprising at least one passage for slidingly receiving the rod        with a preset valgus angle and a distal end face being adapted        for abutting against on the distal face of the femur of either        left leg or right leg dependent on its two flip orientations: in        a first flip orientation the rod can be inserted in a selected        one of the at least one passage having the preset valgus angle        for one of the left and right legs, and in a second flip        orientation after the distal femoral jig being flipped over        about 180° about a jig longitudinal axis the rod can be inserted        in a selected one of the at least one passage having the preset        valgus angle for the other one of the left and right legs.

The distal femoral cutting apparatus of the present invention has areduced number of components, can reduce cost and improve cleanabilityand sterilisation.

The distal femoral jig assembly according to the present invention canbe used for resecting either left or right femur with the simplifiedflip feature which has different preset valgus angles and candramatically simplify the operation procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described below by way of example withreference to the accompanying drawings, in which:

FIG. 1 is a perspective view of distal femoral cutting apparatus in oneof valgus angles in a first flip orientation.

FIG. 2A is another perspective view of the distal femoral cuttingapparatus in accordance in another valgus angle in the first fliporientation.

FIG. 2B is a side view of a rod assembly of the distal femoral cuttingapparatus.

FIG. 2C is view of another rod assembly of the apparatus.

FIG. 3A is an exploded view showing a distal femoral cutting block and adistal femoral jig assembly of the distal femoral cutting apparatus ofFIGS. 1 and 2.

FIG. 3B is an enlarged view showing a part of a distal femoral jigoutrigger of the distal femoral jig assembly shown in FIG. 3A.

FIG. 4 is a side view of the distal femoral cutting block and the distalfemoral jig assembly assembled together.

FIG. 5A and FIG. 5B are side views of the assembled distal femoralcutting block and the distal femoral jig assembly shown in FIG. 4 withdifferent heights.

FIG. 6 is an exploded view showing the distal femoral cutting block andthe distal femoral jig outrigger assembled together and a distal femoraljig being taken a flipping action.

FIG. 7A is a view showing the first flip orientation of the distalfemoral jig and FIG. 7B is a view showing a second flip orientation ofthe distal femoral jig after being taken the flipping action as shown inFIG. 6.

FIG. 8A is a view showing a drill drilling a hole in a distal femur andFIG. 8B is a view showing the drill enlarging the hole in the distalfemur.

FIG. 9 is a view showing a rod with a handle of the distal femoralcutting apparatus is inserted into the hole formed in the distal femurof FIG. 8A and/or FIG. 8B.

FIG. 10 is a view showing the distal femoral jig sliding on the rod andabutting against a distal face of the distal femur.

FIG. 11 is a view showing assembling of the distal femoral jig outriggerto the distal femoral cutting block.

FIG. 12 is a view showing assembling of the assembled distal femoral jigoutrigger and the distal femoral cutting block to the distal femoral jigabutting against the distal face of the distal femur of FIG. 10.

FIG. 13 is a view showing that the distal femoral cutting apparatus isaffixed to the distal femur by fasteners.

FIG. 14 is a view showing that the distal femoral jig assembly isdisengaged with the distal femoral cutting block.

FIG. 15 is a view showing a saw blade extending through a cutting slotof the distal femoral cutting block to resect the distal femur.

DETAILED DESCRIPTION OF THE INVENTION

Unless otherwise defined, all technical and scientific terms used hereinin their various grammatical forms have the same meaning as commonlyunderstood by the skilled reader. The terms anterior, posterior,proximal, distal, medial, lateral, sagital, coronal, and transverse areused herein with their conventional medical/anatomical meaning. Whenused in connection with the distal femoral cutting apparatus, the termsproximal and distal reference the surgeon using the apparatus. Incontrast, when used in connection with the femur with which the distalfemoral cutting apparatus is used, the terms proximal, distal, anteriorand posterior reference the patient. As mentioned above, the term“valgus angle” means the angle between the axis of the main body and thechannel being considered. In the case of the femur, the valgus angle isthe angle formed between the anatomic axis of the patient and thelongitudinal axis of the femur, and in the case of the jig, the valgusangle means the angle between the axis of the jig and the passages inthe jig.

FIGS. 1 to 15 show distal femoral cutting apparatuses. The distalfemoral cutting apparatus is designated generally by reference numeral10 and can guide a saw blade during resection of a distal face of afemur at an angle relative to the patient's intramedullary canal priorto implanting a femoral component of a total knee prosthesis. Inparticular, the distal femoral cutting apparatus 10 can be used forresecting either the left or right femur with preset valgus angles. Thestructure and operation of the cutting apparatus 10 will be described indetail as below.

FIGS. 1 and 2A show in different visual angles the cutting apparatus 10attached to the distal femur 1 of the patient in different preset valgusangles in a first flip orientation. The cutting apparatus 10 comprises arod assembly 20 having a longitudinal axis I-I and adapted for insertinginto the intramedullary canal of the femur, a distal femoral cuttingblock 30 configured for guiding a saw blade to resect the femur, and adistal femoral jig assembly 50 capable of appropriately positioning thedistal femoral cutting block 30 on either left leg or right leg withdifferent preset valgus angles via the rod assembly 20. The distalfemoral jig assembly 50 comprises a distal femoral jig 80 capable ofsliding on a rod 21 of the rod assembly 20 and abutting against a distalface of the femur. The distal femoral jig assembly 50 further comprisesa distal femoral jig outrigger 60 having at least one leg for insertinginto corresponding at least one hole of the distal femoral jig 80 and aclip 64 for engaging with the distal femoral cutting block 30 toposition it. The distal femoral jig 80 has at least one passage forreceiving the rod 21 with different valgus angles and can be adapted forleft leg and right leg with a “flip” feature having a first fliporientation and a second flip orientation, in the first fliporientation, the rod 21 can be inserted in a selected one of the atleast one passage having a preset valgus angle for one of the left andright legs, and in a second flip orientation by flipping over the distalfemoral jig 80 about 180° about its axis from the first fliporientation, the rod 21 can be inserted similarly alternatively in aselected one of the at least one passage having a preset valgus anglefor the other one of the left and right legs.

The rod assembly 20 comprises the elongate rod 21 extending along thelongitudinal axis I-I and used for inserting into the medullary canal ofthe femur. The rod assembly 20 also comprises a handle 22 for removeablyattaching to the rod 21. As shown in FIGS. 2A and 2B, the elongate rod21 has a proximal end 24 and a distal end 25, and the handle 22 has ablind hole 23. The proximal end 24 has a section 26 formed with externalscrew thread and the blind hole 23 is formed with internal screw threadfor mating with the screwed section 26 of the proximal end 24 of the rod21. Other arrangements can be used to connect the rod 21 to the handle22 releasably. For example, as shown in FIG. 2C, the proximal end 24 mayhave a squared section 26′, and the handle 22 has a squared blind hole23′ for receiving the squared section 26′ and a traverse hole 27communicating with the squared blind hole 23′ for receiving a pin 28.When the squared section 26′ of the rod 21 is inserted into the squaredblind hold 23′, the pin 28 may be inserted into the pin hole 27 and abutagainst a side of the squared section 26′ to prevent it from moving. Ofcourse, the shape of the blind hole of the handle 22 is not limited tothe square shape. It may be in a polygonal shape and the proximal end 24has a corresponding shaped section for mating with the blind hole.

Other arrangements can be used to connect the handle 22 to the rod 21.In addition, the rod 21 and the handle 22 may be formed integrally.

FIG. 3A shows the distal femoral cutting block 30 which comprises a mainbody 31. The main body 31 is left-and-right symmetrical and has a frontsurface 41, a vertical rear surface 36, an upper surface 40, a lowersurface 42 and two side surfaces (see FIGS. 3A and 4). The lower surface42 has a curved lower surface portion 38 generally conforming to thehuman anatomy of the anterior distal femur and a substantially flatlower surface portion 39 (best shown in FIGS. 4, 5A and 5B). With such acurved lower surface portion 38, when being positioned on the distalfemur of the patient, the distal femoral cutting block 30 may bepositioned more stably. Preferably, the upper surface 40 is also acurved surface for avoiding any injury to the patient or the surgeon.The main body of the distal femoral cutting block may instead have othershaped surfaces, such as completely flat lower and/or upper surfaces, orstepped lower and/or upper surfaces, or inclined lower and/or uppersurfaces. In addition, as shown in FIGS. 1, 2A and 3A, the main body 31has a smaller front end and a bigger rear end so that the surgeon maymanipulate the cutting block conveniently. However, the shape of thecutting block is not limited to the illustrated one, and other shapesfor the main body may be used.

As shown in FIGS. 2A and 3A, the main body 31 has several groups ofthrough holes passing through the main body from the upper surface 40 tothe lower surface portion 38. The through holes of the first group areconvergent (or angled) holes 32 for receiving pins (such as pins soldunder the trade mark SP2 by Ethicon Endo-Surgery Inc.) to fix the distalfemoral cutting block 30 to the anterior femur. The through holes of thesecond group are reposition holes 33 for receiving pins (such asSteinmann pins) which allow the distal femoral cutting block 30 to beadjustable.

As shown in the embodiment of FIG. 2A, there are two convergent holes 32which are arranged left-and-right symmetrically. Of course, the numberof the convergent holes may be increased or reduced as desired, and theycan be symmetrical or unsymmetrical as long as they can fix the distalfemoral cutting block 30 to the anterior femur. Furthermore, theconvergent holes can be omitted since appropriate arranged repositionholes can also fulfill the function of fixation.

In the constructions shown in FIGS. 2 and 11, there are totally eightreposition holes 33 with four reposition holes 33 on the left side ofthe upper surface 40 and four reposition holes 33 on the right side ofthe upper surface 40 which allow the distal femoral cutting block 30 tobe adjustable. As can be seen in FIG. 11, the arrangement of the fourreposition holes 33 on the left side of the upper surface 40 is the sameas that on the right side of the upper surface 40. Specifically, thefour reposition holes 33 on either side are arranged in two longitudinallines and staggered with each other. In the shown example, the firstreposition hole on the left line is taken as a reference and marked as“0” position. As shown in FIG. 4, when assembled together, a distancebetween a distal end surface of the distal femoral jig 80 and a distalwall forming a cutting slot 35 in the distal femoral cutting block 30 is9 mm and inserting two pins into the “0” position reposition holes willfix the resecting depth as 9 mm, which is used as a basic or referenceresecting depth. The other repositions holes 33 allow the distal femoralcutting block 30 to be adjustable from 9 mm (see FIG. 4) by +4 mm, +2mm, −2 mm so that the resecting depths are adjusted correspondingly as13 mm, 11 mm and 7 mm for different patients. The number of thereposition holes may be increased or reduced and other arrangement ofthe reposition holes may be adopted for flexibly adjusting the resectingdepth as desired.

A central hole 34 is provided on a central portion of the upper surface40 of the cutting block 30 for receiving a tip end 68 of the clip 64 ofthe distal femoral jig assembly 50. On a central portion of the verticalrear surface 36 of the cutting block 30, there is a big central opening37 for receiving a trunion 69 of the distal femoral jig assembly 50. Thecentral axes of the central hole 34 and the central opening 37 may be ormay not be in a perpendicular position relationship, and the hole 34 andthe opening 37 may be or may not communicate with each other. As shownin FIG. 3A, the central hole 34 is in a rectangular shape. However, itis not necessary for the central hole 34 to be a rectangular hole, othershapes such as a semi-circular shape may be suitable as long as thecentral hole 34 can receive the tip end 68. As can be seen from FIG. 3A,the central opening 37 is a tapered counterbore. The stepped portion ofthe central opening 37 can prevent the trunion 69 from moving furtherinto the opening 37. The shape of the central opening 37 is not limitedto the shape shown in the drawings, and other shapes (such ascylindrical counter-bore, cylindrical or tapered hole with protrusionsor a shoulder protruding from the inner wall of the hole, and the like)are also suitable for receiving the trunion 69 and preventing it fromfurther moving.

The cutting slot 35 is formed in a proximal portion of the main body 31and parallel with the vertical rear surface 36 of the main body 31. Asshown in FIG. 3A, the cutting slot 35 is a through slot which allow asaw blade to pass through so as to cut off a portion of the distalfemur. Although only one cutting slot 35 is shown in the drawings, theremay be a plurality of cutting slots for selectively cutting offdifferent lengths of the distal femur. Moreover, the vertical rearsurface 36 or say the proximal end face of the cutting block 30 may beused as a reference for resection. In the example shown in FIG. 4, theresection initiated from the proximal end face of the cutting block 30will resect 4 mm less distal femur than the resection initiated from thecutting slot. In addition, the plurality of cutting slots may be usedalone or in combination with the reposition holes for adjusting theresecting depths. When the cutting slots are used alone for adjustingresecting depths, the reposition holes may be omitted.

In the construction shown in FIGS. 2A and 3A, the distal femoral jigassembly 50 comprises the distal femoral jig outrigger 60 and the distalfemoral jig 80 supporting the distal femoral jig outrigger 60. Thedistal femoral jig outrigger 60 includes a support 61 and the clip 64supporting by the support 61. The support 61 comprises a beam 62 and atleast one leg extending vertically and downwardly from the beam 62 for aquick connection with the distal femoral jig 80. In the exemplifiedembodiment shown in FIG. 3A, the support 61 has two legs 63 extendingfrom the beam 62 vertically and downwardly so that the support 61 is inan inverted U shape (or generally U shape). The clip 64 includes a baseportion 65 formed integrally with the beam 62 and a movable portion 66capable of pivoting around a pivot pin 67 passing through the pinhole inthe base portion 65 via a spring (not shown in the figures). The baseportion 65 has the trunion 69 at its front end for insertion into thecentral opening 37 and two side walls protruding from the beam 62 forprotecting the spring. In the example shown in FIG. 3A, the trunion 69has a substantially cylindrical portion and a truncated cone portionhaving a biggest diameter smaller than the diameter of the cylindricalportion. The truncated cone portion of the trunion 69 is used for easyinsertion into the central opening 37. When the trunion 69 is insertedinto the central opening 37 of the distal femoral cutting block 30, theend face of the cylindrical portion abuts against the stepped portion ofthe central opening 37 for preventing further movement. The trunnion 69and the central opening 37 fit the jig outrigger 60 with the cuttingblock 30, and their shapes may be changed within the spirit of thepresent invention. For example, when the central opening 37 is acylindrical counter-bore or a cylindrical hole with protrusions or ashoulder as mentioned above, the trunion 69 may correspondingly have abigger diameter cylindrical portion and a smaller diameter cylindricalportion. The movable portion 66 has a proximal portion used as a button70 and a distal portion having the hook-like tip end 68. When assembledwith the distal femoral cutting block 30, the trunion 69 is insertedinto the central opening 37, and the tip end 68 bites into the centralhole 34. Of course, the tip end 68 may have other shapes as long as itcan bite into the central hole 34 for a quick connection. At least oneof the legs 63 has a groove 72 formed circumferentially around its lowerend (see FIGS. 3A and 3B). As best shown in FIG. 3B, a C-clip 71 isarranged in the groove 72. When the two legs 63 are inserted into thedistal femoral jig 80, the C-clip(s) 71 can provide friction to preventthe distal femoral jig outrigger 60 from sliding off the jig 80, asdescribed below.

FIGS. 3A, 7A and 7B show the distal femoral jig 80 in detail. Inparticular, FIG. 7A and FIG. 7B are views respectively showing the firstflip orientation and the second flip orientation of the distal femoraljig 80. In the device shown in the drawings, the distal femoral jig 80has a longitudinal axis II-II (as shown in 3A) and comprises a guidingbar 81 extending along the longitudinal axis II-II for guiding the rod21, a positioning block 82 formed integrally at a distal end of theguiding bar 81 for a quick connection with the jig outrigger 60 andabutting against the end face of the distal femur, and at least onepassage 84 extending through the jig 80, i.e., the guiding bar 81 andthe positioning block 82, with a preset valgus angle towards the femurfor slideably receiving the rod 21 so as to position the cutting block30 with the preset valgus angle. The positioning block 82 may be formedseparately and then attached to the distal end of the guiding bar 81 byknown means. The positioning block 82 is formed with a vertical distalend face perpendicular to the longitudinal axis II-II for stablyabutting against the end face of the distal femur. The positioning block82 is also formed with at least one vertical through hole 89 forreceiving the at least one leg 63 of the distal femoral jig outrigger60. Due to the at least one vertical through hole 89, directly flippingover the distal femoral jig 80 can still allow the at least one leg 63to be inserted through the at least one vertical through hole 89 so asto easily connect the jig outrigger 60 and the jig 80 together.Meanwhile, due to the vertical distal end face and the at least onepassage 84 with the preset valgus angle, before flipping over the jig80, i.e., in the first flip orientation, the assembled cutting apparatuscan be used for resecting the distal femur of one of the left and rightlegs, and after flipping over the jig 80, i.e., in the second fliporientation, the assembled cutting apparatus can be used for resectingthe distal femur of the other one of the left and right legs.

As an example, two passages 84 extend throughout the distal femoral jig80, i.e., the guiding bar 81 and the positioning block 82, towards thefemur for passage of the rod 21. The two passages 84 each have a valgusangle with respect to the longitudinal axis II-II of the distal femoraljig 80. In the construction shown in the drawings, the two passages 84extend in a convergent manner from a proximal portion to a distalportion of the distal femoral jig 80, i.e, toward the femur. In anexample, though the two passages 84 are arranged in the convergentmanner, they do not meet at one point but the extension lines of thecentral lines of the two passages meet at a point. In another example,the central lines of the two passages meet at a point on the distal faceof the jig 80. The arrangement of the one, two or more passages are notlimited to the convergent manner. For example, the passages may bearranged in a divergent manner. In such a divergent manner, the startingpoints of the two or more passages may be or may not be one and the samepoint.

In the construction shown in the drawings, one of the two passages 84has a valgus angle of 5° with respect to the jig longitudinal axis II-IIand the other one of the two passages 84 has a valgus angle of 7° withrespect to the jig longitudinal axis II-II, such that the distal femoraljig 80 can be rotated (or say “flip”) either clockwise (see FIG. 6) orcounterclockwise to provide the 5 and 7 degree angles settings for eachleg: for example, one side has 5° left and 7° right, the opposite sidehas 7° left and 5° right (as shown in FIGS. 6, 7A and 7B). The valgusangles may be different from 5° or 7°, as long as the valgus angledifference between the two passages is between 1° and 3° and the twovalgus angles both are selected between 4° and 10°.

As mentioned above, at least one passage is provided in the distalfemoral jig 80. If there is only one passage formed in the distalfemoral jig, then the preset valgus angle for the left leg and the rightleg by flipping over the distal femoral jig is the same. If there aretwo or more passages formed in the distal femoral jig, then the presetvalgus angles for the patient can be selected as desired.

For the convenient grip of the surgeon, the guiding bar 81 may have atapered shape or a truncated cone shape as shown in FIGS. 7A and 7B.This is not necessary. For example, it may have a funnel shape. Othershapes might be used.

As mentioned above, the positioning block 82 is used for a quickconnection with the jig outrigger 60 and abutting against the end faceof the distal femur. In the construction shown in FIG. 3A, thepositioning block 82 comprises the vertical distal end faceperpendicular to the jig longitudinal axis II-II for abutting the endface of the distal femur and two vertical through holes 89 for receivingthe two legs of the jig outrigger 60. Such structure allows the jig 80to flip over for the use of either left or right leg distal femurresection. In the specific example shown in the FIG. 3A, the positioningblock 82 is a substantially cuboid having two parallel front and rearsurfaces perpendicular to the jig longitudinal axis II-II and twoparallel upper and lower surfaces. The two vertical through holes 89extend from the upper surface to the lower surface of the positioningblock 82 for receiving the two legs 63 of the distal femoral jigoutrigger 60. When the jig outrigger 60 has at least one leg, thepositioning block 82 may be correspondingly provided with at least onevertical through hole for receiving the at least one leg. Oralternatively, the positioning block 82 may be provided with verticalthrough holes more than the legs of the jig outrigger 60 for selectivelyreceiving the legs of the jig outrigger 60. Although the shape of thepositioning block 82 shown in the example is a substantially cuboid andsymmetrical with respect to a vertical plane passing through the jiglongitudinal axis II-II and with respect to a horizontal plane passingthrough the jig longitudinal axis II-II, the shape of positioning block82 is not limited to the above mentioned one, it may be a regular orirregular shape, symmetrical (for example, only symmetrical with respectto the vertical plane passing through the jig longitudinal axis II-II oronly symmetrical with respect to the horizontal plane passing throughthe jig longitudinal axis II-II) or unsymmetrical, as long as itcomprises the vertical distal end face perpendicular to the jiglongitudinal axis II-II for abutting the end face of the distal femurand at least one vertical through hole for receiving the at least oneleg of the jig outrigger 60. As used herein, term “vertical” means it isperpendicular to the “horizontal” plane formed by the passages 84. Thus,the vertical rear surface 36, the legs 63 and the through holes 89 areall perpendicular to the horizontal plane formed between the passages 84(more than merely perpendicular to the jig longitudinal axis II-II).

In the construction shown in FIG. 3A, the positioning block 82 includestwo fixation through holes 85 extending from the front surface to therear surface of the positioning block 82 for receiving two pins toprovide optional fixation of the jig 80 on distal femur. The number ofthe fixation through holes may be increased or reduced as desired, andthe axes of the fixation through holes may be or may not be parallelwith the jig longitudinal axis II-II, as long as pins may be passedthrough those fixation through holes and fixed the jig 80 onto thedistal femur.

The positioning block 82 shown in the embodiment of FIG. 3A alsocomprises two optional stop plates 86 protruding respectively from itsupper and lower surfaces at the distal end of the positioning block 82and each having a recess 88 formed at a central portion. The stop platesare used for abutting against on the end face of the distal femur. Asmentioned above, the distal end face of the positioning block 82 per secan be used for abutting against the end face of the distal femur, andthe two stop plates 86 may be omitted. The recess 88 of each stop plate86 has a shape conforming to the bottom shape of the base portion 65 ofthe distal femoral jig outrigger 60. Furthermore, since the distalfemoral jig is for medical use, preferably, the left and right sides ofthe positioning block 82 are rounded to avoid injury or trauma. Morepreferably, the stop plates 86 and the left and right sides of thepositioning block 82 are all rounded to avoid injury or trauma.

Due to the at least one vertical through hole of the distal femoral jig80, the at least one vertical leg of the distal femoral jig outrigger 60can be inserted into the distal femoral jig 80 from both sides, allowingthe apparatus to flip round (see FIGS. 6, 7A and 7B). Due to such a flipfeature, the cutting apparatus can be adapted to both left leg and rightleg with a simple structure and simplified operation. In particular, thedistal femoral jig 80 comprises two flip orientations: in the first fliporientation (as shown in FIG. 7A) the rod 21 can be inserted in aselected one of the at least one passage having a preset valgus anglefor one of the left and right legs, and when the distal femoral jig 80is flipped over about 180° about its axis (best shown in FIG. 6) to thesecond flip orientation (as shown in FIG. 7A) the rod 21 can be insertedsimilarly alternatively in a selected one of the at least one passagehaving a preset valgus angle for the other one of the left and rightlegs. In the embodiment of FIG. 7A and FIG. 7B for a patient with aboutsymmetrical skeletal anatomy having the same valgus angle (on theopposite sides of the anatomical axis) for both the left leg and theright leg, inserting the rod 21 into a passage before flipping thedistal femoral jig fits a first leg (e.g. left leg) and after flippinginserting the rod 21 into the same passage fits the other leg (e.g.right leg) at the same valgus angle (e.g., 7°). Thus, having twopassages suitable for use with flipping adaptation for two preset valgusangles (such as 5° and 7°) the distal femoral jig provides forflexibility of having two valgus angles to select from for both the leftleg and the right leg. More than two passages might be used.

When the at least one leg 63 of the jig outrigger 60 is inserted intothe respective at least one through hole 89 of the jig 80, the trunion69 of the jig outrigger 60 is inserted into the central opening 37 ofthe cutting block 30, and the tip end 68 bites into the central hole 34,the cutting block 30, jig outrigger 60 and jig 80 are assembledtogether. Due to the leg and hole assembling manner of the at least oneleg 63 of the jig outrigger 60 and the at least one through hole 69 ofthe jig 80, the cutting block 30, jig outrigger 60 and jig 80 can beassembled/disassembled quickly and easily. In addition, also due to theleg and hole assembling manner, the apparatus may be adjusted todifferent femurs having much different sizes. When in use, the distalfemoral cutting block 30 will be positioned on the distal femur of thepatient and the distal end face of the distal femoral jig 80 will abutagainst the end face of the distal femur. Taking the distance betweenthe substantially flat lower surface portion 39 of the cutting block 30and the longitudinal axis II-II of the distal femoral jig 80 as ameasure, the cutting block can be adjusted from a minimum of 13 mm atthe lowest point as shown in FIG. 5A and a maximum of 50 mm at thehighest point as shown in FIG. 5B. At the lowest point, the base portion65 of the outrigger 60 is positioned in the recess 88 of the stop plate86 and the distal face of the beam 62 abut against the stop plate 86. Atthe highest point, the C-clip 71 provides friction to prevent theoutrigger 60 from sliding off the jig 80. So the cutting apparatusaccording to the present invention can be applied on much differentpatients.

All of the elements of the cutting apparatus are formed by medical usematerials, such as medical grade stainless steel, a nickel-titaniumbased alloy such as Nitinol, and the like. The cutting apparatus isprovided non-sterile and stored in a sterilization case. It can besterilized using an approved sterilization method as stated in theappropriate instructions for use (IFU) document.

FIGS. 8A to 15 show the operation of the cutting apparatus according tothe present invention.

With the patient's knee in flexion, a surgeon may remove osteophytesfrom the intercondylar notch to clear the position. Since correctlocation of the medullary canal is critical to avoid malposition of thefemoral component, the following procedure must be implemented carefullyto avoid the cortices. The surgeon firstly positions a drill to enterthe medulary canal slightly superior and medial to the midline of thetrochlea, 7 mm to 10 mm anterior to the origin of the posterior cruciateligament (see FIG. 8A). In the proper position, the drill should passeasily into the femoral canal.

The diameter of the hole drilled in the distal femur could be increasedif required (see FIG. 8B). This will allow depressurization of the canalwhen the rod is inserted.

When a desired hole is drilled in the knee, the surgeon introducesslowly the rod 21 of the rod assembly 20 into the medullary canal to thelevel of the isthmus L (see FIG. 9). As mentioned above, the rod 21 aidsto relieve intramedullary pressure. The rod assembly 20 is subsequentlywithdrawn. Please note that although the above procedure illustrates theFemur First technique, the present technique can also be performed usingthe Tibia First approach.

The surgeon may use preoperative radiographs to define the angle betweenthe femoral anatomical and mechanical axes. According to the specificdimension of the knee of the patient, the surgeon may select theappropriate valgus angle (for example, left or right: 5° or 7°) (FIGS.7A and 7B) of the distal femoral jig by sliding the jig 80 onto the rod21 towards the femur until the distal end face of the jig or the stopplates 86 of the jig contact the end face of the distal femur (see FIG.10). If the surgeon worries about the positioning of the distal femoraljig 80, pins may be inserted into the fixation holes 85 to fix the jig80 to the distal femur.

The surgeon may then assemble the distal femoral cutting block 30 to thedistal femoral jig outrigger 60 by inserting the trunion 69 into thecentral opening 37 and simultaneously pressing the button 70 of theoutrigger 60 (see FIG. 11) to let the tip end 68 bite into the centralhole 34. After that, the surgeon can put the assembled cutting block 30and the outrigger 60 above the distal femoral jig 80 and position the atleast one leg 63 into the at least one hole 89 of the jig 80 until thecutting block 30 touches the anterior femur (see FIG. 12). Then theapparatus is in a state as shown in FIG. 1 or 2A.

When the surgeon opines that the cutting block 30 is properlypositioned, he or she may insert two pins (such as Steinmann pins)through the reposition holes 33 marked with “0” into the posteriorcondyles to fix the cutting block 30 onto the distal femur, as shown inFIG. 13.

The surgeon could appropriately arrange the cutting block 30 onto thedistal femur by a series of adjusting motions. The surgeon may then pushthe button 70 using his thumb to release the tip end 68 from the centralhole 34 so that the distal femoral jig assembly 50 is released from thecutting block 30. The surgeon may withdraw the jig assembly with onehand as shown in FIG. 14.

Of course, even at this step, the surgeon still has a chance to adjustthe position of the cutting block 30 due to the reposition holes 33. Tofurther adjust the distal resection depth once the distal femoral jigassembly 50 is removed, the surgeon may use the distal or proximalreposition holes 33, which move the cutting block (for example, 2 mm inthe device shown in the drawings) in distal direction or (for example, 2mm or 4 mm in the device shown in the drawings) in proximal direction(FIG. 13). Furthermore, if it is necessary for additional stability, thesurgeon may insert one or more pins (for example Steinmann pins) throughone or more of the convergent pin holes 32 on the cutting block 30.

The cutting block 30 is left on the distal femur. Now the surgeon mayuse a saw blade to resect the distal face of the femur via the cuttingblock 30. As described above, the cutting block 30 is formed with one ormore (or say at least one) cutting slots 35. The saw blade may beinserted into one of the cutting slots 35 to resect corresponding depthof the femur (see FIG. 15). Alternatively, the surgeon may initiate theresection from the proximal end face 36 of the cutting block 30, whichis parallel with the cutting slots and this will resect 4 mm less distalfemur.

The surgeon may remove the pin from the convergent pin hole 32 and thedistal femoral cutting block 30 once the resection has been completed.If further resection is needed, the surgeon may leave the fixation pinsin place for refining the distal femoral cut by adjustment the positionof the distal femoral cutting block 30.

The fixation pins are also removed once the resection is finished.

The invention claimed is:
 1. A distal femoral jig assembly used with acutting apparatus for resecting a distal face of a femur prior toimplanting a femoral component of a total knee prosthesis, the cuttingapparatus comprising: (i) a rod adapted for inserting into anintramedullary canal of the femur, and (ii) a distal femoral cuttingblock configured for guiding resection of the distal face of the femur,in which the distal femoral jig assembly is capable of positioning thedistal femoral cutting block on either a left leg or a right leg andcomprises a distal femoral jig and a distal femoral jig outrigger havingat least one vertical leg, the distal femoral jig comprising: (a) apositioning block having a distal end face which is adapted for abuttingagainst the distal face of the femur, and at least one vertical throughhole extending through it from an upper surface to an opposite lowersurface thereof, the through hole being configured to receive thevertical leg on the outrigger, and (b) a guiding bar which is formedintegrally with the positioning block and extends proximally from thepositioning block, the guiding bar extending along a longitudinal axisof the jig which extends perpendicular to the distal end face of thepositioning block, in which first and second passages extend through theguiding bar and the positioning block, in a convergent manner in adirection towards the patient's femur when the jig is in use, the firstand second passages each being configured for slidingly receiving therod with respective first and second preset valgus angles, and in whichthe distal end face of the positioning block can abut against on thedistal face of the femur of either the left leg or the right legdependent on two flip orientations in which, in a first flip orientationthe rod can be inserted in a selected one of the first and secondpassages having an appropriate preset valgus angle for one of the leftand right legs, and in a second flip orientation after the distalfemoral jig being flipped over approximately 180° about a jiglongitudinal axis the rod can be inserted in a selected one of the firstand second passages having the appropriate preset valgus angle for theother one of the left and right legs.
 2. The distal femoral jig assemblyaccording to claim 1, in which the distal femoral jig is adapted toallow the rod to be inserted in the selected one of the first and secondpassages, resulting in the valgus angle for the left leg and the rightleg being the same by flipping over the distal femoral jig.
 3. Thedistal femoral jig assembly according to claim 1, in which a valgusangle difference between the two passages is 1° to 3° and the two valgusangles both are between 4° and 10°.
 4. The distal femoral jig assemblyaccording to claim 3, in which the two passages are adapted forreceiving the rod for sectioning the femur corresponding to a 5° valgusangle and a 7° valgus angle.
 5. The distal femoral jig assemblyaccording to claim 1, in which the positioning block comprises two stopplates protruding from the upper surface and the lower surface and at adistal end of the positioning block.
 6. The distal femoral jig assemblyaccording to claim 1, in which the distal femoral jig outrigger has asupport having a beam and the at least one leg extending from the beamvertically and downwardly and a clip arranged on the beam, the cliphaving a hook-like tip end for biting into a central hole formed in theupper surface of the distal femoral cutting block.
 7. The distal femoraljig assembly according to claim 6, in which at least one leg of the atleast one leg of the distal femoral jig outrigger has a groove formedcircumferentially around its lower end and a C-clip is arranged in thegroove for providing friction to prevent the distal femoral jigoutrigger from sliding off the distal femoral jig.
 8. The distal femoraljig assembly according to claim 6, in which the distal femoral jigoutrigger further comprises a trunnion extending distally from the beamfor inserting into a central opening formed in the proximal surface ofthe distal femoral cutting block.
 9. The distal femoral jig assemblyaccording to claim 8, in which the trunnion comprises a substantiallycylindrical portion and a truncated cone portion having a largestdiameter smaller than a diameter of the cylindrical portion, the centralopening of the distal femoral cutting block is a tapered counterborehaving a stepped portion.
 10. The distal femoral jig assembly accordingto claim 9, in which the positioning block comprises two stop platesprotruding from the upper surface and the lower surface and at a distalend of the positioning block and in which each stop plate has a centralrecess conforming to a bottom shape of a base portion of the trunnion.11. The distal femoral jig assembly according to claim 10, in which theguiding bar has a tapered shape or a cone shape.
 12. The distal femoraljig assembly according to claim 10, in which the positioning blockincludes at least one fixation hole extending through the positioningblock from a proximal surface to a distal surface.
 13. A cuttingapparatus for resecting a distal face of a femur prior to implanting afemoral component of a total knee prosthesis, comprising: (a) a distalfemoral jig assembly as claimed in claim 1, (b) an elongate rod adaptedfor inserting into an intramedullary canal of the femur, and (c) adistal femoral cutting block configured for guiding resection of thedistal face of the femur.
 14. The cutting apparatus according to claim13, in which a handle is removably attached to, or formed integrallywith, a proximal end of the rod for withdrawing the cutting apparatus.15. The cutting apparatus according to claim 13, in which the distalfemoral cutting block comprises at least one slot for selectivelycutting off different lengths of the distal femur.